Tris(2-aminoethyl)amine

Metal complexes

Tren is a C3-symmetric, tetradentate chelating ligand that forms stable complexes with transition metals, especially those in the 2+ and 3+ oxidation states. Tren complexes exist with relatively few isomers, reflecting the constrained connectivity of this tetramine. Thus, only a single achiral stereoisomer exists for [Co(tren)X₂]⁺, where X is halide or pseudohalide. In contrast, for [Co(trien)X₂]⁺ five diastereomers are possible, four of which are chiral. In a few cases, tren serves as a tridentate ligand with one of the primary amine groups non-coordinated. Tren is a common impurity in the more common triethylenetetramine ("trien"). As a trifunctional amine, tren forms a triisocyanate when derivatized with COCl₂.

TREN is known to react fast in the presence of (aromatic) aldehydes to form an imine. During this process, water is formed, making it a condensation reaction. Due to this fast and efficient reaction, TREN is commonly used in the preparation of polyimines.

N-methylated derivatives

The permethylated derivative of tren has the formula N(CH₂CH₂NMe₂)₃. "Me₆tren" forms a variety of complexes but, unlike tren, does not stabilize Co(III). Related amino-triphosphines are also well developed, such as N(CH₂CH₂PPh₂)₃ (m.p. 101-102 °C). This species is prepared from the nitrogen mustard N(CH₂CH₂Cl)₃.

N,N,N-trimethyltren, N(CH₂CH₂NHMe)₃ is also available.

Safety considerations

(H₂NCH₂CH₂)₃N, like other polyamines, is corrosive. It causes severe skin burns and eye damage, is harmful if inhaled due to the destruction of respiratory tissues, is toxic if swallowed, and can be fatal in contact with skin. Its median lethal dose is 246 mg/kg, oral (rat), and 117 mg/kg, dermal (rabbit). It is also combustible.